+1 to what Theo has said.
My pond ices over throughout the winter. I keep a small hole open in the ice, as so many of us do. There are a couple dozen trout, rainbows and tigers, in the pond, along with assorted panfish and bass. When my pond becomes ice free, as it did a 2 weeks ago, I start "testing the waters" with a small handful of Optimal BG and mealworms.
Trout feeding activity arrived with gusto a week after the ice went off. Nary a splash before that.
I shut down my aerator when the first ice off occurs, knowing that regardless of complete ice cover building each night, this thin sheet will be gone mid the next day. And, even though the shoreline is covered with snow, last night I witnessed several sunfish coming up slowly and carefully for food. Because of the lighting, I couldn't positively ID both green and bluegill sunfish, but I'm imagining I saw both. No YP yet.
All this is to say I threw about a half cupful of food to the sunfish. They ate only some of that. The trout moved in later and cleaned up the remainder. There are thousands of BG and GSF in the pond. Right now they ate less than a half cup of food.
Be careful to not overfeed. There are threads on the forum discussing BG eating but not properly digesting fish food when the water is cold. Feed very sparingly if at all; monitor the consumption. In my not expert opinion, your water quality may be better and your fish healthier if you feed less than they can clean up than if you add excess nutrients by giving the fish too much.
